Aid workers have warned that cold weather in the Himalayan foothills, where temperatures have already fallen below freezing, may claim more lives after the magnitude-7.6 quake Oct. 8 left about 87,000 dead and 3.5 million homeless.

Poor visibility forced a suspension of flights by helicopters from the United Nations, foreign militaries, and Pakistan's army, which have been delivering winterized tents, clothes, food, and other supplies to survivors, said an air force officer at Chaklala air base, near the capital, Islamabad.

The weather is expected to clear up enough for flights to resume by late today, he said on condition of anonymity, in line with Pakistani government policy.

The United Nations estimates 2.5 million people are living in tents at elevations below 5,000 feet and as many as 400,000 others are in higher areas where it is feared that snow and rain will make it harder for helicopters and trucks to reach them.

Cold rain pelted the quake zone throughout yesterday, and about 12 inches of snow fell above the 6,000-foot level, said Qamar-uz Zaman Chaudhry, head of Pakistan's Meteorological Department.

Yesterday evening, heavy snow also blanketed Muzaffarabad, the capital of Pakistan's portion of Kashmir and the supply center for the humanitarian operation. Residents reported that roads leading to the mountains were blocked by vehicles stuck in snow.

Chaudhry said more snow and rain were probable over the next two days.

As the cold chilled sprawling tent cities that have sprung up in Pakistan's northwest and in Kashmir, survivors struggled to keep warm around campfires and candles, exposing them to another danger.

Police said three young sisters died Saturday when a fire swept through a tent in Gul Deri, a village in the northwest. A candle started a blaze inside a tent that the family pitched next to their home, which was destroyed by the quake, Samar Khan, a police official, said.

Last month, seven people, including four children, died in a similar accident, and UN officials said they had started teaching people how to make safe fires.

In Muzaffarabad and nearby areas, survivors said the rain and snow were making their lives difficult.

Sajjad Ali Shah, a 38-year-old at a damp, riverside camp in Muzaffarabad, said people had dug drains around their tents to keep out rainwater, but the ground had become soaked.

''We wrap our children in blankets, but it is very cold," he said.

In snow-covered Sudhan Gali, a high mountain village south of Muzaffarabad, Shabbir Ahmed Khan expressed fear that canvas tents might not be able to withstand the weather.

''Our houses have been destroyed in the earthquake and these tents are not sufficient to protect us from snow. There is no place where we can hide ourselves," said Khan, a former soldier. ''We need steel sheets for shelter. Our children are shivering with cold."

Ithar Jan Bibi, a woman in another village near Muzaffarabad, said she was running out of food that aid workers distribute every 15 days, and she was not sure whether the weather would delay the next handout.

''I cannot make fire in the tent and I do not have dry wood to burn," she said. ''It is impossible to fetch water in the snow."

Major Farooq Nasir, an army spokesman in Muzaffarabad, said army engineers would keep roads open when bad weather grounds helicopters.

The army said it has stored seven days of food supplies at 16 emergency supply bases in areas likely to be cut off by heavy snow.

The Pakistani-administered part of Kashmir suffered the most casualties from the quake. India controls the other part of the divided territory, but both countries claim it in its entirety.